Menu - I don't have all the details, but I know they were talking teriyaki chicken and rice or something they could pick up in bulk at Costco.

Decorations - I believe they just got lanterns and several things from Oriental Trading Co.
I am going to suggest to her black poster boards painted with gold paint with borders and look up some characters and paint them in the middle to mount on the walls so it kind of looks like a chinese restaurant.

Cheap and easy.